Which clause returns unique values for a column in a SELECT statement?

• A. GROUP BY
• B. ORDER BY
• C. DISTINCT
• D. WHERE

Answer: (C)

Returning unique values in a query is accomplished by using DISTINCT. DISTINCT looks at the values you select and removes duplicates, so each value appears only once in the result. If you select a single column, you get all its distinct values. If you select multiple columns, DISTINCT returns unique combinations of those columns rather than deduplicating each column independently. In contrast, GROUP BY groups rows by column values and is typically used with aggregates to produce one result per group; ORDER BY just sorts the final rows; WHERE filters which rows are included but does not remove duplicates by itself. Therefore, to obtain a list of unique values for a column, use DISTINCT, for example: SELECT DISTINCT country FROM customers;